We are pursuing an in-depth investigation on the structure and function of the membrane receptor for IgE. For these studies intact cells from a rat basophilic leukemia and a mouse mastocytoma as well as normal rat and mouse mast cells are being used. In addition receptor-bearing membrane particles and solubilized receptors are being studied, with the aim of understanding the structure of the receptor as well as its integration in the membrane. Results of such studies as well as direct functional studies are aimed at understanding the early steps in the cellular triggering by an antigen-induced, antibody-mediated reaction. BIBLIOGRAPHIC REFERENCES: Rossi, G., Newman, S.A. and Metzger, H.: Assay and partial characterization of the solubilized cell surface receptor for Immunoglobulin E. J. Biol. Chem. 252: 704-711, 1977. Newman, S.A., Rossi, G. and Metzger, H.: Molecular weight and valence of the cell-surface receptor for Immunoglobulin E. Proc. Nat'l. Acad. Sci., U.S.A. 74: 869-872, 1977.